Simple, Your BRAIN can only process so much, so the signal to your vocal cords and tongue slow and You mess up Example:
SAY PETER Piper picked a pack a pickle peppers 8x
Did you mess up? I bet so
also here an easy one. RUBER BABY BUGGY BUMPER
The appropriate answer is D ! in this the dominant allele is not fully dominant ! this is seen in Snapdragon !
so answer is D